U.S. patent number 6,080,252 [Application Number 08/944,480] was granted by the patent office on 2000-06-27 for zipper component and method for forming same.
This patent grant is currently assigned to Illinois Tool Works Inc.. Invention is credited to Eric P. Plourde.
United States Patent |
6,080,252 |
Plourde |
June 27, 2000 |
Zipper component and method for forming same
Abstract
An zipper component is formed by extruding a flange, extruding a
profile, depositing the flange onto the top surface of a continuous
carrier web, depositing the profile onto the top surface of the
flange, cooling the flange and profile and stripping the flange and
profile from the carrier web for further processing.
Inventors: |
Plourde; Eric P. (Tinley Park,
IL) |
Assignee: |
Illinois Tool Works Inc.
(Glenview, IL)
|
Family
ID: |
25481480 |
Appl.
No.: |
08/944,480 |
Filed: |
October 6, 1997 |
Current U.S.
Class: |
156/66;
264/211.12; 264/177.1; 264/176.1; 264/177.17; 264/177.19; 156/247;
156/244.18; 156/289; 156/244.25; 24/DIG.50; 156/244.11;
156/764 |
Current CPC
Class: |
B29D
5/10 (20130101); B65D 33/2508 (20130101); B29C
48/07 (20190201); B29C 48/08 (20190201); B29C
48/9145 (20190201); B29C 48/12 (20190201); Y10S
24/50 (20130101); Y10T 156/1978 (20150115); B29C
48/001 (20190201); B29C 48/154 (20190201); B29C
48/16 (20190201); B29C 48/22 (20190201) |
Current International
Class: |
B29D
5/00 (20060101); B29D 5/10 (20060101); B29C
47/00 (20060101); B29C 47/88 (20060101); A41H
037/00 () |
Field of
Search: |
;156/66,244.11,244.18,247,289,344,244.25 ;24/587
;264/176.1,177.1,177.17,177.19,211.12,178R,348 ;493/211,215 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Yao; Sam Chuan
Attorney, Agent or Firm: Pitney, Hardin, Kipp and Szuch
LLP
Claims
What is claimed is:
1. A method of making a zipper component, to be fused to a
substrate comprising the steps of:
extruding a zipper flange substantially smaller than 6 mils
directly onto a top surface of a carrier web, said carrier web
having a texture and being formed in an endless loop whereby said
texture is imparted to a bottom surface of said zipper flange;
extruding a zipper profile onto a top surface of said zipper
flange;
carrying said zipper flange directly on a top surface of said
carrier web and carrying said zipper flange and said zipper profile
on said carrier web in an un-set condition without imparting
tensile forces to said un-set zipper flange and profile; and
stripping said zipper flange from said carrier web after said
profile has been extruded onto said zipper flange and said zipper
flange and said zipper profile have set on said carrier web.
2. The method according to claim 1, wherein said zipper component
is stripped from said carrier web before completing a circuit
around a path of said carrier web.
3. The method according to claim 1, further comprising the step of
cooling said portion of a zipper component with water after the
step of extruding said zipper component.
4. The method according to claim 1, further comprising the step of
applying a release agent to said top surface of said carrier web
before the step of extruding said zipper component.
5. The method according to claim 1, further comprising the step of
changing a temperature of said carrier web in at least one location
to facilitate adhesion of said zipper component to said carrier
web.
6. The method according to claim 1, further comprising the step of
changing a temperature of said carrier web in at least one location
to facilitate release of said zipper component from said carrier
web during the stripping step.
7. The method according to claim 1, wherein said profile and said
flange are formed of differing polymeric resins.
8. The method according to claim 1, comprising the further steps
of:
extruding another profile, said another profile having a mating
configuration to said zipper profile;
depositing said another profile onto said top surface of said
flange in parallel relationship with said zipper profile; and
carrying out said stripping step after said flange, said zipper
profile and said another profile have set.
9. The method according to claim 1, comprising the further step of
extruding a sealant onto at least one surface of said flange.
10. The method according to claim 1, comprising the further step of
extruding a sealant onto at least one surface profile.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a zipper component tape or strip for
resealable plastic bags and the like and a method for forming the
zipper component. More particularly, this invention relates to a
zipper component wherein a continuous molten stream of
thermoplastic material is formed as a base and brought into contact
with a continuous carrier web driven by a series of rollers. Mating
profiles are extruded onto the base, and the extrudate is stripped
from the carrier web before the extrudate makes a complete circuit
around the web.
2. Description of the Prior Art
In known processes for forming extruded zipper profiles for
resealable plastic bags such as that described in U.S. Pat. No.
4,741,789, a base member is extruded and deposited onto a bag film
web. A profile member is thereafter extruded and deposited onto the
base member, thus adhering the profile to the bag film web. Because
the profile and base members are deposited directly onto the bag
film web immediately after extrusion, the bag film web must be of
such a material and configuration as to be subjected to the
disclosed process. Thus, the effectiveness of such processes is
limited.
U.S. Pat. No. 4,894,975 discloses a method of manufacturing
reclosable plastic bags in a vertical form and seal machine wherein
a strip or tape carrying the profiles is used to provide the
closure for the bag and to complete the bag formation.
U.S. Pat. No. 5,188,461 describes a method of manufacturing profile
portions for packings, wherein the profiled portion is not
deposited directly onto the packing. According to the method
disclosed, a profiled outer layer is secured to an intermediate
binding layer, which is secured to a base layer. The base layer is
preferably made of the same material as the packing, allowing the
base layer to be secured to the packing. By requiring the foregoing
three layers, the disclosed method is not cost effective.
Other known methods of forming zipper components have used the
extruded profile to pull itself through the equipment for
manufacturing the same. To minimize deformation of the extruded
profile due to tensile forces created in such methods, it is
necessary to cool and solidify the extrudate as quickly as possible
after extrusion. Water baths and cooled air have been utilized to
cool and solidify the extrudate. However, such quenching methods do
not permit typical post-extrusion forming of the extrudate.
Further, such quenching methods do not eliminate deformation of
relatively small unsupported profiles by tensile forces caused by
the manufacturing equipment.
Therefore, in order to alleviate these problems, it is an object of
the present invention to provide a zipper component and a method
for forming a
zipper component which does not expose the extruded profile to
potentially damaging forces. Another object of the present
invention is to provide a zipper component and a method for forming
a zipper component wherein a support for the extruded profile does
not become part of the finished zipper component. Yet another
object of the present invention is to provide a low-cost method for
forming a zipper component.
SUMMARY OF THE INVENTION
The above and other beneficial objects are obtained in accordance
with the present invention by providing a method of forming a
zipper component wherein a carrier web is temporarily utilized to
provide a stable base for an extrudate while the extrudate is in an
unsolidified and relatively unstable state.
BRIEF DESCRIPTION OF THE DRAWINGS
In the accompanying drawings:
FIG. 1 is a block diagram of the method according to the present
invention;
FIG. 2 is a side elevational view of an apparatus employing the
method according to the present invention; and
FIG. 3 is a section view taken along reference lines 3--3 of FIG.
2.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The foregoing figures illustrate a zipper component and a method of
forming a zipper component in which identical numerals in each
figure represent identical elements.
FIG. 1 illustrates a block diagram of the method of forming a
zipper component in accordance with the present invention, and FIG.
2 illustrates an apparatus 10 for forming a zipper component
according to the method of the present invention. First, in step
100, a flange 16 is extruded by a flange die 12. Next, in step 102,
a profile 18 is extruded by a profile die 14. Preferably, flange 16
and profile 18 are each made of a polymeric resin. Depending upon
the intended application of flange 16 and profile 18, it may be
preferable to select differing materials for flange 16 and profile
18.
Next, in step 104, flange 16 is deposited onto the top surface of a
continuous carrier web 20 in the area of carrier web 20 generally
supported by cast roller 24. A sealant material may be co-extruded
onto one or both surfaces of flange 16 before depositing flange 16
onto carrier web 20, or a sealant material may be extruded onto the
upper surface of flange 16 after depositing flange 16 onto carrier
web 20 prior to depositing profile 18 onto flange 16 as described
below. Carrier web 20 forms an endless loop around cast roller 24,
driving roller 26 and stripping roller 28 and is driven by driving
roller 26. Driving roller 26 is driven by an electric motor or
other driving means, not shown. Adjusting/steering roller 30 is
provided between stripping roller 28 and cast roller 24 to adjust
and maintain the tension of carrier web 20. Carrier web 20 may be
made of a suitable material, such as Teflon, to which flange 16
will not adhere or conditioned to prevent adherence or slippage.
The top surface of carrier web 20 may have a texture 38, as shown
in FIG. 3, such as a grid-like texture. The particular texture of
the carrier web 20 is imparted to the flange 16 to increase the
capability of flange 16 to bond to a substrate in such intended
applications as recloseable plastic bags. By imparting a grid-like
structure to the surface of flange 16 and bonding flange 16 to a
substrate, fluid leaks between the bonded surface of flange 16 and
the substrate are minimized or eliminated, requiring such fluids to
follow a tortuous path to subtend the bonded flange 16. At least
the top surface of carrier web 20 may also have a treatment to
provide adequate adhesion so that flange 16 does not intermittently
slip and reattach to carrier web 20 and to allow release of flange
16 at the stripping point 36 as described below. The treatment may
consist of raising or lowering the temperature of carrier web 20 at
specific points to facilitate such adhesion and detachment, or the
treatment may be a release agent being applied to the top surface
of carrier web 20 prior to depositing flange 16 thereon.
Next, in step 106, profile 18 is deposited onto the top surface of
flange 16 or onto the top surface of the sealant material if a
sealant material is co-extruded onto the top surface of flange 16
as described above. While the material selected for flange 16 may
differ from the material selected for profile 18, the materials
selected should permit profile 18 to bond with flange 16 and permit
flange 16 to bond with the substrate. Obviously, numerous shapes
are available for profile 18, and only a representative shape is
depicted. Next, in step 108, flange 16 and profile 18 are cooled by
adjusting/cooling nozzle 22, thereby stabilizing and setting flange
16 and profile 18. Water may be ejected from adjusting/cooling
nozzle 22 to cool flange 16 and profile 18. As illustrated in FIG.
2, carrier web 20 is disposed vertically between cast roller 24 and
driving roller 26, which ensures that any water deposited on flange
16 and/or profile 18 during cooling will be removed. While flange
16 and profile 18 are carried by carrier web 20, no tensile forces
are imparted on flange 16 or profile 18 to guide flange 16 and
profile 18 through the apparatus 10. Thus, deformation of flange 16
and profile 18, even when flange 16 and profile 18 are relatively
small, is eliminated.
Finally, in step 110, flange 16 and profile 18 are stripped from
carrier web 20 at the stripping point 36. The stripping point 36 is
in the general area of carrier web 20 where the path of carrier web
20 turns about stripping roller 28. Flange 16 and profile 18, after
being stripped from carrier web 20, are guided through top take-off
roller 32 and bottom take-off roller 34 for further processing,
such as rolling and storing, shipping or application to a
substrate.
It will be appreciated that flange 16 and profile 18 will be
supported by carrier web 20 while flange 16 and profile 18 are in
an unsolidified and relatively unstable state. It will be further
appreciated that while flange 16 and profile 18 are in such an
unsolidified and relatively unstable state, the apparatus 10 does
not impart tensile forces to deform flange 16 or profile 18. As
carrier web 20 provides a stable base for flange 16 and profile 18
during setting, post-extrusion forming of the profile 18 or forming
a relatively small unsupported flange 16 and profile 18 is
possible. Finally, because carrier web 20 does not form an integral
part of the finished product, no material is lost in the process,
thereby reducing costs.
Advantageously, flange 16 is formed to a thickness of 2 to 8 mils,
compared with traditional zipper components having a flange
thickness of at least 6 mils. By forming flange 16 with a thickness
of, for example, 2 mils, the temperature required for fusing flange
16 to a substrate, such as a bag film, not shown, is reduced from
approximately 280 degrees for a typical 6-8 mils thickness flange
16 to approximately 245 degrees for a 2 mils thickness flange 16
formed in accordance with the present method. By reducing the
fusing temperature of the flange 16, the speed of fusing the zipper
component is thereby increased. Similarly, the zipper component
formed according to the method of the present invention eliminates
the need to pre-soften or stamp the zipper for side sealing
effectiveness since less material is available to soften and act as
a heat sink than traditional zipper components.
As described above, flange 16 is first deposited onto the top
surface of carrier web 20, and profile 18 is then deposited onto
the top surface of flange 16. Alternatively, flange 16 and profile
18 may be extruded and deposited onto the surface of carrier web 20
simultaneously, either as discrete components or as a single
component, or a so-called string zipper.
In the above description, a single profile 18 is depicted on flange
16. If desired, such as for applications as described in the
aforementioned U.S. Pat. No. 4,394,975, a pair of mating profiles
18 could be deposited in parallel relationship onto the same flange
16 to provide a zipper tape. Thus, a male profile 18 and female
profile 18' could both be deposited onto flange 16 as shown in FIG.
3, wherein the optional profile 18' is shown in phantom.
Thus the several aforementioned objects and advantages are most
effectively attained. Although a single preferred embodiment of the
invention has been disclosed and described in detail herein, it
should be understood that this invention is in no sense limited
thereby and its scope is to be determined by that of the appended
claims.
* * * * *